Beginning from the recently proposed identification as the Navalia of the great building in opus incertum in Testaccio, Rome, represented in the Severian Marble Plan and already attributed to porticus Aemilia, the contribution traces a link between the harbour functions of the ancient Emporium and the altar in the Musei Capitolini with dedication to Mater Deum and Navisalvia and illustration of the myth of Claudia Quinta Vestal towing in to safety the ship of Cybele arriving at Ostia in 204 B.C. With regard to the dating of the altar to the Julio-Claudian age, particularly significant appears, moreover, the development promoted in the cult of the Magna Mater by the emperor Claudius (institution of Hilaria, supposed foundation of Phrygianum at the Vatican, etc.), and therefore the highly 'pervasive' dimension that it will come to assume in the topography of Rome from this age on.
